1. Field of the Invention
The present invention relates to a novel process for production of hydroxocobalamin.
2. Related Art
Various cobalamin--series compounds including hydroxocobalamin are mainly derived from Co-enzyme type vitamin B.sub.12 produced by fermentation. It is known in the art that the Co-enzyme type vitamin B.sub.12 is optically converted to hydroxocobalamin (see, vitamin Science (II) Water Soluble Vitamin, P 493, Tokyo Kagaku Dojin).
It has been believed, however, that direct isolation and purification of hydroxocobalamin from Co-enzyme type vitamin B.sub.12, which is present in a very low concentration among various impurities is very difficult, because hydroxocobalamin is highly reactive and unstable. For example, Japanese Examined Patent Publication (Kokoku) No. 39-18148 (GB 1012360) describes "the case wherein hydroxocobalamin is directly produced from a fermentation broth is very difficult because hydroxocobalamin is highly reactive and hydroxocobalamin easily binds to other ions present in a solution . . . ", and this is generally recognized in the art.
Therefore, hydroxocobalamin is obtained from Co-enzyme type vitamin B.sub.12 produced by fermentation by a process comprising the steps of conversion of Co-enzyme type vitamin B.sub.12 to stable cyanocobalamin, purification of the cyanocobalamin, and conversion of the purified cyanocobalamin to hydroxocobalamin (see, Japanese Examined Patent Publication No. 39-18148, and Japanese Examined Patent Publication No. 46-14664 (U.S. Pat. No. 3448099)).
However, the process wherein hydroxocobalamin is obtained from coenzyme-type vitamin B.sub.12 going through cyanocobalamin as an intermediate is not advantageous with respect to yield, production costs, and the like. Such a process requires numerous, complex steps. In particular, coenzyme-type vitamin B.sub.12 is first converted to cyanocobalamin; the cyanocobalamin is isolated and purified in a sub-process requiring several steps; the purified cyanocobalamin is converted to hydroxocobalamin; and, finally, the hydroxocobalamin is isolated and purified.